Retrieve Fields/Parts Values in Rules e.g. Email

I am having a problem to retrieve specific values for fields/parts within a rule (send an email).
I got a Custom form with taxonomy fields/inputs/textares/fileuploadpart, it is no problem to get the values of the inputs and texareas with e.g.: {Content.Fields.Application.Title} or by using {Request.Form:xxx}, the problem is I am not able to get the values
of the taxonomy fields and the FileUploadPart, whatever combination of naming I use the values are always empty.